Radio-frequency electrocautery ablation of mammary tissue in swine

PURPOSE: To establish the size, configuration, and histopathologic features of acute, subacute, and chronic radio-frequency (RF) electrocautery of mam mary tissue in swine. MATERIALS AND METHODS: Eighteen RF treatments were performed in the mammary tissue of three domestic swine under ultrasonographic (US) guidance. Histo pathologic examination was performed immediately after (acute animal); 2 we eks after (subacute animal); and 4 weeks after (chronic animal) treatment. RESULTS: in the acute animal, lesions were firm nodules on palpation and ha d a distinct line of demarcation between necrotic and viable mammary tissue (mean lesion volume, 14.24 cm(3); largest volume, 29.06 cm(3)). In the sub acute animal, there was diffuse coagulation necrosis with neutrophilic infi ltrates at the periphery (mean lesion volume, 6.46 cm(3); largest volume, 9 .47 cm(3)), and two treatment areas had a secondary bacterial infection. In the chronic animal, lesions were still palpable and firm (mean lesion volu me, 11.67 cm(3); largest volume, 25.5 cm(3)), and five of six treatment sit es had an area of gray to white fibrotic tissue that blended with the surro unding tissue. However, one site had a pale yellow area of central necrosis surrounded by a fibrotic area. In both the subacute and chronic animals, t wo and one treatment site, respectively, had minimal areas of skin necrosis . CONCLUSION: RF ablation of breast tissue is feasible in this animal model. Problems included minimal skin erythema, residual firm treatment regions at 4 weeks, slightly variable margins of coagulation necrosis, and occasional bacterial infection.